//==========================================================================
// Copyright (c) 2000-2008,  Elastos, Inc.  All Rights Reserved.
//==========================================================================
/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001, 2002 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: pushpull.h,v 1.4 2006/05/16 14:15:00 shijun Exp $
 *
 */

#ifndef __PUSHPULL_H__
#define __PUSHPULL_H__

struct pushpull
{
    unsigned char *buf;
    unsigned int buflen;
    unsigned int ofs;
    unsigned int reserve;
};

static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen,
                unsigned ofs, unsigned reserve)
{
    pp->buf = buf;
    pp->buflen = buflen;
    pp->ofs = ofs;
    pp->reserve = reserve;
}

static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)
{
    if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) {
        return ENOSPC;
    }

    if (bit) {
        pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7)));
    }
    else {
        pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7)));
    }
    pp->ofs++;

    return 0;
}

static inline int pushedbits(struct pushpull *pp)
{
    return pp->ofs;
}

static inline int pullbit(struct pushpull *pp)
{
    int bit;

    bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;

    pp->ofs++;
    return bit;
}

static inline int pulledbits(struct pushpull *pp)
{
    return pp->ofs;
}

#endif /* __PUSHPULL_H__ */
